Credits

Wednesday, September 19, 2007

Tonight I went to a presentation of the results of an initial Phase II Comprehensive Site Assessment of the Sawins and Williams Pond property located at Arlington Street and Coolidge Avenue here in Watertown. Sawins Pond is privately owned and the assessment was carried out on behalf of the property owner. Both ponds are currently contaminated and fenced off. They're filled with muck, barrels, and a lot of old rubber from the former BF Goodrich site which used the pond as a landfill. Any potential cleanup would not be financed by the town. The assessment was tasked with finding the potential sources of contaminants. Their scope was limited to PCBs, metals, petroleum products, etc, and they did not look at any biological contaminants such as human or animal waste. There were about a dozen people in attendance.

The company doing the assessment, Vineyard Engineering, took 17 sediment samples, six soil samples, surface water from five locations and groundwater from 14 onsite wells. The water in the ponds is only a few inches deep on top of several feet of muck and during the sampling, Vineyard did not get the sense that there was any current dumping going on.

Fifteen of the sediment samples had high levels of PCBs, particularly in the western part of Williams Pond, close to Elm St. There was not as much where the water's deeper, but PCBs were found in the sediment throughout both ponds. Metals found in the sediment followed the same profile as PCBs. The found higher than acceptable amounts of six metals: Cadmium, Copper, Lead, Mercury, Nickel and Zinc. EPH (petroleum) and SVOC (semi-volatiles) concentrations were found in Williams Pond and under the Arlington street culvert. Ten volatile organic compounds were also found, with acetone most prevalent (though thismay be caused by natural anaerobic fermentation processes). Gasoline leakage from motor vehicles may be a primary source of some of these compounds.

So, while the sediment seems to be extremely contaminated, the surface water was a different story. There were no PCBs detected in the surface water. This was mostly expected, as they don't tend to enter the water body very easily. Only five metals were detected in the water, with nickel the most common at low levels. A little bit of arsenic was also present, but not mre that would be expected in an urban environment. There was no apparent source of either, however. In addition, the surface water contained no petroleums, only small SVOCs at very low levels. No volatile Petroleums or Organic Compounds apart from Xylene at low levels.

The soil tests revealed no soil PCBs apart from one boring with a very small amount. There were slightly elevated levels of Beryllium, Chromium and Nickel (with no explanation). There were surprisingly low levels of Lead and Mercury in the soil, considering the high levels in the sediments. One soil sample smelled of gasoline and had high levels of VOCs. There was so much rubber on the site, it's impossible to not get any rubber in your sample, but that was outside of the scope of the project.

As for the groundwater, no PCBs were found. There were only trace levels of Arsenic and Zinc, well below the standard. Only Xylene was detected above the risk standard.

The study concluded that the North bank of Sawins Pond needs further evaluation, as does the source of Petroleum-related hydrocarbons. That may be reflective of garbage that fills the pond, or it may be runoff from the road. The representative from Vineyard noted that a likely source of the PCBs was a 1983 release of about 500 gallons of PCBs into the ponds from a nearby Boston Edison (now NStar) facility. They did a cleanup then, the levels they found after the cleanup are consistent with what we have today. In addition, in 1979, there was an oil spill in Sawins pond. There have apparently been many releases on the NStar property. NStar may be responsible for cleanup of the sediments.

I spoke briefly with the presenter after the meeting, and he noted that any such cleanup of the sediment would cost millions of dollars, and he couldn't speculate on what the end result would look like. After all, the woods around the area would have to be cleared for roads so that trucks can be loaded with the toxic muck and cart it away. He imagined two craters where the ponds once stood after all was said and done. Alternatively, they could "cap" the sediment and divert the water into culverts that would lead to the Charles River. In any event, it may take another century to return Sawins Pond back to the condition it was when a fancy hotel sat on its banks over 100 years ago.